Catalytic asymmetric epoxidations are extremely useful methods for synthesizing chiral compounds and consequently these types of reactions have broad applicability in the pharmaceutical industry. In the early 1980's Sharpless disclosed an effective method for accessing chiral epoxy alcohols, using a titanium-tartarate complex in the presence of a stoichiometric achiral oxidant. Although this process consistently provides high enantioselectivity, it has a number of disadvantages, which include the required use of molecular sieves, the sensitivity of the catalyst system to air and water, and an extensive and complicated work-up.
The catalytic asymmetric oxidation, disclosed herein, has one or more of the following advantages over previously used methods. Because the catalyst system is not water sensitive, molecular sieves are not required and an aqueous solution of an organic hydroperoxide can be used as the achiral oxidant. The catalyst system is not air sensitive the reactions are performed under aerobic conditions. Reactions can be easily worked up, which makes this system much more amenable to large-scale reactions. This methodology can also be applied to the catalytic asymmetric oxidation of phosphines and sulfides.